wiki:Component/VciDma

SocLib Components General Index

VciDma

1) Functional Description

This VCI component moves data from a source memory buffer to a destination memory buffer. It is both a target and an initiator.

  • It is addressed as a target to be configured for a transfer.
  • It is acting as an initiator to do the transfer.

There is only one DMA context handled at a time. An IRQ is optionally asserted when transfer is finished. This hardware component checks for segmentation violation, and can be used as a default target.

This component has 5 memory-mapped registers :

  • DMA_SRC (Read / Write)

It defines the physical address of the source buffer.

  • DMA_DST (Read / Write)

It defines the physical address of the destination buffer.

  • DMA_LEN (Read / Write)

It defines the length of transfer, in bytes. This register must be written after writing into registers DMA_SRC & DMA_DST, as the writing into the DMA_LEN register starts the transfer. This register gets back to 0 when transfer is finished. This register can be used to test the DMA coprocessor status.

  • DMA_RESET (Write-only)

Writing any value into this pseudo-register makes a clean re-initialisation of the DMA coprocessor: The on-going VCI transaction is completed before the coprocessor returns the IDLE state. This write access must be used by the software ISR to aknowledge the DMA IRQ.

  • DMA_IRQ_DISABLED (Read / Write)

A non zero value disables the IRQ line. The reset value is disabled.

For extensibility issues, you should access the DMA using globally-defined offsets.

You should include file soclib/dma.h from your software, it defines DMA_SRC, DMA_DST, DMA_LEN, DMA_RESET, DMA_IRQ_DISABLED.

Sample code:

#include "soclib/dma.h"

static const volatile void* dma = 0xc0000000;

void * memcpy(void *dst, const void *src, const size_t len)
{
    soclib_io_set( dma, DMA_DST, dst );
    soclib_io_set( dma, DMA_SRC, src );
    soclib_io_set( dma, DMA_LEN, len );
    while( soclib_io_get( dma, DMA_LEN ) )
        ;
    return dst;
}

(add -I/path/to/soclib/include to your compilation command-line)

2) Component definition & usage

source:trunk/soclib/soclib/module/infrastructure_component/dma_infrastructure/vci_dma/caba/metadata/vci_dma.sd

See SoclibCc/VciParameters

Uses( 'vci_dma' )

3) CABA Implementation

CABA sources

CABA Constructor parameters

VciDma(
     sc_module_name name,   //  Component Name
     const soclib::common::MappingTable &mt,   // MappingTable
     const soclib::common::IntTab &srcid,  // Initiator index
     const soclib::common::IntTab &tgtid,  // Target index
     const size_t burst_size );   //  Number of bytes transfered in a burst

CABA Ports

  • sc_in<bool> p_resetn : Global system reset
  • sc_in<bool> p_clk : Global system clock
  • soclib::caba::VciTarget<vci_param> p_vci_target : The VCI target port
  • soclib::caba::VciInitiator<vci_param> p_vci_initiator : The VCI initiator port
  • sc_out<bool> p_irq : Interrupt port

4) TLM-DT implementation

The TLM-DT implementation is not available yet.

Last modified 10 years ago Last modified on Jun 22, 2012, 2:11:41 PM